The practice of excessive caloric restriction through reduced intake is pandemic and has its origin during adolescence. While factors such as low self-esteem, substance use, poor body image and depression are associated with unhealthful regulation practices among adolescent females, prospective studies are needed to identify risk factors. Once risk factors for developing unhealthful weight regulation practices are known, it may be possible to develop preventive interventions. The primary purpose of this proposal is to examine a set of variables which may serve as risk factors for the adoption of unhealthful weight regulation strategies including excessive dieting and self-induced vomiting for weight control. Secondary objectives are to a) determine the usefulness of somatomedin-C as an index of nutritional status, b) determine longitudinal patterns of changes in height, weight, skinfold thickness and body mass index from ages 11 to 13 in relationship to stage of pubertal development, nutrition, activity and weight regulation habits. All 6th and 7th grade females (ages 11 to 13, N= ~950) in six middle schools in Santa Clara, California will be assessed in September 1988, 1989, and 1990 with a variety of instruments. Physiologic measures: height, body weight, skinfold thickness and Tanner self-staging. Biological measures: serum cholesterol and somatomedin-C. Self-report behaviors: demographics, family weight history, knowledge, and attitudes about weight regulation, assessment of weight-regulation behaviors, activity in Kcal expenditure/week, and food frequency for the past month. Average daily calories, saturated fat, cholesterol, protein, and carbohydrate intake will be calculated from the food frequency. Psychological measurements: the Eating Disorder Inventory (EDI): measures of body image, depression, anxiety, self-esteem and family attitudes and value, Exposure to and involvement with mass media will be measured. Students will also be assessed once every three months with a partial assessment battery consisting of weight, height, pubertal development, EDI, weight regulation behaviors and restraint scale. The relative risk of the various factors will then be determined. These risk factors can then serve as a basis for preventive interventions.